


A Demon Most Familiar

by Strawberrybats



Series: Another Modern Supernatural AU, Wow [1]
Category: Love Live! School Idol Project, Love Live! Sunshine!!
Genre: Alternate Universe, Body Horror, F/F, Modern Magic, Supernatural Elements, as soon as yall read that tag u can Guess who inspired this one
Language: English
Status: In-Progress
Published: 2017-06-28
Updated: 2017-06-28
Packaged: 2018-11-20 02:18:07
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,719
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11326599
Author URL: https://archiveofourown.org/users/Strawberrybats/pseuds/Strawberrybats
Summary: In retrospect, maybe trying a high-level summoning ritual for a demon familiar without any parental supervision was a bad idea. Not that anything before that point had ever stopped Yoshiko from making a series of foolish mistakes before, but still. She didn't think the spell would interpret her incantation *that* way.(Modern magic/supernatural au where yoshiko is a beginner level witch with the world's most godawful luck and summoning spells are like petulant genies just looking for a chance to misinterpret your every request.)





	A Demon Most Familiar

**Author's Note:**

> i started writing this like two weeks ago with the intent to scratch mochi's monsterfucking itch so it's basically yours man 
> 
> shout out to anyone else who reads this tho you're all champs. why do you put up with these indulgent aus

“ _To best complete the spell, ritual circles should be exactly one meter in diameter, and each subcircle should one foot. Pentagrams are unhelpful, unless they are involved in the binding contract for the demon summoned.”_  

Yoshiko hums, making a few minor adjustments to her chalk circle, then hits the pause button on her laptop. Now, if this webinar - _Demon Companions And You: 6 Simple Steps To Satan -_ was correct, then if her circle was laid out properly, a demon would surely answer her request.

Hopefully. She knows she’s taking somewhat of a risk, invoking this kind of ritual while her parents are out on a meeting for the Uranahoshi Coven Association, but she’s a big girl now, and sometimes teenagers just have to call upon demons for companionship when their moms are busy and can’t teach them any spells! That’s all!

She takes a deep breath, and places her palms on two circles on opposite ends, funneling as much magic as she can into the piece. The circle begins to glow. “O great Satan, send a demon familiar to me, so that we may preserve your knowledge in this mortal realm together....” uhhh, fuck, what was the next part? “With this summoning contract I abide my energies to be used as you please..” so far so good...nothing has blown up, at least. The light flickers, How promising!

Yoshiko continues undeterred now. “And hope with all my heart that my desire for a demon companion is fulfilled!.....Thanks.” She removes her hands and lets out a deep breath. Yikes, her arms feel like lead pipes. She must have pumped more magic than she thought into that one. Whatever! It just means she’s probably going to get a cooler demon, right?

....She should probably clean this circle up. From her understanding the demon doesn’t need to use it as a portal, or else it’d have continued glowing - according to the webinar, anyways. She shuts her laptop and dutifully begins to scrub the chalk and summoning salt off the floor, careful to blow out all the candles in such a way as to cause no offense to any spirits that might interpret it as disrespect. Now to sit back and wait.....

Her phone buzzes in her pocket a few times. A phone call? Who _calls_ people anymore, don’t they know Yoshiko speaks exclusively over text? Maybe it’s one of her moms taking a break from the witch gathering and checking in on her. Yoshiko pulls the phone out.

Dia? This just keeps getting weirder. Dia barely deigns to speak with her in person, enough to almost make Yoshiko forget she’d even given her her phone number. Is something up?

She slides the answer button and greets her cheerfully. Or, well, she would, if Dia wasn’t already talking. A lot. Dazed, Yoshiko tries to catch as much of the word jumble being thrown at her as she can.

"-and I'm calling _you of all people_ because I don't know anyone else that might have a way to stop it and -" From the second Yoshiko answers the call, Dia is rattling off words like she’s going to have her supply of them cut off in the next minute. She isn't even sure what the first half of the call was _about_.  Eventually, she has to interrupt, gracefully.  
  
"Wh - uh - why - s-slow down! I can't hear what you're asking!" Eloquent. Artful, even. Yohane, master of spells, summons and social situations.  
  
Dia is still incredibly flustered on the other line, but has the presence of mind to take a deep breath and try again. "Something is happening to Ruby, and we need your help. I don't know any other witches that might be able to get a hold on the situation."  
  
This gets her attention rather quickly. "Ruby? What's happening, is she okay -" if Dia is calling for help whatever is going on must be magic related, but Ruby doesn't have a scrap of magic in her body, and a curse seems too outrageous an explanation, too - who would lift a finger against poor sweet Ruby? Dia is one thing, but _Ruby._...  
  
"She's...." Dia pauses on the other line, like she's swallowing, or perhaps glancing over at her sister in distress. "...changing. And it doesn't look like lycanthropy, or else I would have called Chika. Now _please_ , come help us. Loathe as I am to admit it, I'm helpless. Magic caused this, and magic can fix it.....right?" For someone as strong-willed as Dia, the weak note at the end makes the situation that much more dire. If Dia is this worried, and not in any sort of over-exaggerated way, then Yoshiko should be too.  
  
Spurred on perhaps by some inner strength, or the determination to play the hero in front of Ruby, Yoshiko's focus seems to converge all on this moment: there is no time to waste.  
  
"I'll be at your house as fast as I can. Keep an eye on anything unusual." She hangs up.  
  
Whatever is happening, it's far from what Yoshiko had expected. Somehow when she'd thought of the words “changing”, “Ruby”, and “magic’”, she'd worked it into some strange, fae like situation. a shining girl in a cocoon of glitter, emerging with one or two traits from the fair folk. A harmless charm Mari might have cast to screw with Dia. Not -  
  
Not whatever THIS is.  
  
For a few extremely distressing moments, Yoshiko is convinced that Ruby must be bleeding. What else could be happening? Deep gashes, dark red patches blooming from them - it had to be blood. But the closer she got, the less sense it made. the gashes were closed, the deep red was...solid? It started to look more like her skin was developing ridges, and the color was filling in afterwords, spreading like watercolor paint. Turning red.  
  
" _Well???_ " Dia asks, impatiently, fervently, almost, and she's still flitting about ruby with a damp washcloth, as if wiping up her sweat is also going to magically rub off the tainted looking skin. "What the hell is happening to her?!"

"I-I don't know," Yoshiko stammered honestly. "It looks like a curse spell, but I don't know what the intended effect could be. I've never used magic like this...."  
  
Ruby squirms on the couch like that girl from _The Exorcist_ and when she turns herself over onto her stomach there are two suspiciously tight mounds, running down the length of her back, and _eww_ , _gross_ , isn't this the time for something to block her vision or for the magic, shiny light to encase her? But nothing of the sort happens and Yoshiko is forced to stand and watch batlike wings emerge like some sort of alien species hatching out of a corpse in a horror movie.

Whatever is left behind from the ‘hatching’ on the couch is, at the very least, not bloodied. looks like that hardened skin really was like scale - if Yoshiko hadn't watched the whole thing and thrown up in her mouth a little bit, she might have thought the sheet of _Ruby’s literal back skin_ was from a naga in shed.  
  
On the couch, Ruby coughs. Yoshiko can't stand just looking on anymore. "I haven't figured out the cause yet, so I can't stop it...but may I at least cast a pain relief spell?"  
  
"Please." Dia must be even more miserable than she is - hell, she might even feel worse than Ruby right now. Yoshiko mutters the words to herself until she's pretty sure she has them in the right order and there is a sudden, blissful sigh from the couch. It doesn't stop whatever is going on, of course, but at least Ruby is in a better state. Ruby needed so much pain relief that she might as well have knocked her out.  
  
Dia paces while Yoshiko flips through her grimoire for anything relevant, and Ruby starts to take up more of the couch than she used to. Yoshiko is oblivious.  
  
"Curses, hexes, and the time to use them....no. Transfiguration and you: All kinds of selves....not exactly.....demonic...possession?" She skims each section (not unlike cramming for a history test, probably, she’s sure if there _is_ relevant information she'll find it even when she’s skimming, right?) and the last seems most likely. Sometimes a demon will latch onto and begin to affect the appearance of the host, blah blah, this might explain how anyone got it in their mind to be mean to Ruby at least - but then Yoshiko is stuck.  
  
This usually happens over a period of WEEKS?? This is happening like, now! In minutes! She flips a few pages. Faster demon transformations is definitely going to be under transfiguration.  
  
_...it is possible to transfigure other people into demons to act as familiars or servants._  
  
Oh.  
  
Oh no.  
  
Yoshiko furtively looks up. Ruby is growing needly black spines along her arms and back, and the taint has left virtually no human skin behind. horns of pitch black grow out from her forehead and curl like those of a ram's around her head, and she has four hollow eyesockets, each with a trembling green-blue light. Her jaw is more teeth than skin. A long, reptilian tail twists behind her.  
  
Yoshiko draws a deep breath and shuts her book. The air of finality draws Dia's attention. She all but snaps her neck in the speed with which she looks at Yoshiko. "Yes? Did you learn anything?"  
  
For a bit, she keeps her mouth very firmly shut, knowing Dia will rip her to pieces. Still, eventually Yoshiko’s (completely obnoxious) conscience kicks and she decides it’s better to be brutally killed by Dia than to let her family think some evil witch has it out for Ruby.

Maybe being honest will lessen the punishment...? Let her dream.

“This happened as a result of a failed familiar spell.” She says, and judging from Dia’s flat look that’s not enough. “I can’t risk reversing it myself because it might be my fault in the first place.”

“It might be _what_.” Dia’s voice is dripping with fury. Oh gods, satan, anyone – help her.

She flinches. The great and powerful witch Yohane, frightened by a completely magic-less human. Not a good look.

Though she flinched away, Dia surprisingly didn’t start beating on her right away. Though she seemed tempted. With barely concealed agitation, the older girl crossed her arms. “Explain to me what you did. In detail.”

“I wanted to summon a demon that could help me with my spells while my mothers were out of town,” She starts, slowly. “And I followed instructions on a webinar to cast a spell that would summon a demon familiar. Usually, a familiar is a kind of magic being that helps amplify a witch’s spellcasting abilities and gets ingredients for them, but I think……the spell I was working with backfired because I got the words wrong.” She looks down at her hands and touches the tips of her fingers together, anxiously. “It must have been looking for a demon I was _familiar with_ , and since I don’t know any, it, uhh…….well. I’m familiar with Ruby, so……”  

Ugh. Good going, Yohane. How much more incriminating could it get?

“Can you un-cast it?” Dia asks, in a sickeningly sweet tone. It becomes clear at this point that she’s only withholding because she assumes if it’s Yoshiko’s fault there must be a quick fix she can perform.

Too bad for Dia that Yoshiko is a beginner level witch with the World’s Worst Luck. “I don’t know how to undo the ritual! The lesson plan I used didn’t say anything about this kind of mistake because the instructions were so clear!” She stands up and tries to placate Dia. “N-not to worry though! The great Yohane always prevails over misfortune, y’see? Everything I screw up can be fixed! If not by my weakening magical abilities, then by my most excellent lineage!” She strikes her signature fallen angel pose. “In two weeks my family will return from the coven and override my magical signature without fail. So it’s all temporary, really.”

She could hear a pin drop. Yoshiko tries to hold the pose, but she’s sweating. Hard.

“She’s going to be stuck like this…..for _two weeks_?!?! I’ll kill you!” Dia roars, and Yoshiko wisely decides to start running.

“GaaaaaaaaaaaaaahhhHHHHH! D-Don’t scare me like that! P-powerful witches like Yohane can’t be manhandled like this!” Dia lunges at her, intent to give her the throttling of her life. “I-I’ll hex you! I mean it!”

“Sis, I think it really was an accident…..” Both of them stop dead in their tracks at this; how the hell did they forget Ruby was in the room with them? Either Yoshiko’s pain-stopper was better executed than usual, or Ruby is finished with her demon-ification, because she stands up and walks over to the two of them.

…….Jesus _christ_ , she’s tall. Seemingly becoming aware of this herself, Ruby ducks her head and squats down to better get a look at the two of them. The disparity between her voice and appearance almost makes Yoshiko want to laugh, but Dia is still very much in range to smack her if she so chooses.

“…Right, Yoshiko?” Ruby asks earnestly, blinking lidless eyes at her expectantly. It occurs to Yoshiko that she was spacing out.

She bites her lip. “What?”

“This isn’t permanent?”

“O-of course not!” She sputters. “I might have screwed it up, but I’m not anywhere _near_ powerful enough to curse someone for an entire lifetime. It might wear off even before I get my mom to take it off. Seriously!” As if to prove her innocence, she raises her arms in surrender.

“See? I’ll be fine, big sis! Yoshiko didn’t mean to do it.” She’s not sure if it’s intended to be a reassuring smile, mostly because she appears to be lacking lips to smile with, but the little glowy things that seem to be Ruby’s eyes are all squinty little lines instead of circles now, which must mean her eyes are closed?

Dia seems reluctant to accept that line of reasoning, but as always, she doesn’t want to argue with Ruby. She settles down onto the couch and pats the spot next to her. Initially Yoshiko thinks the gesture is intended for her, but when she makes a move to walk Dia gives her a deathly glare. Okay then! That spot is for Ruby. Got it. Message received.

Ruby tries her best to sit as near to Dia as she can, but her progress is notably hindered by her new body. After trying three times to get her wings behind the couch and her butt on top of something other than her tail, she gives up and has Dia move so Ruby can sit down first and seat Dia on her lap. The tail has been craftily wedged between the couch cracks.

She can’t help it.

Yoshiko has been itching to laugh for the past few minutes just out of the sheer absurdity of it all, and this is the final straw. She snorts loudly, despite her best efforts to muffle it with her fist.

“Is something funny, Tsushima?”

“I guess….” Snort. “This makes Ruby the big sister for now?”

She doesn’t care if she dies now. That was too funny not to say out loud.

* * *

After sending Yoshiko home the first day, Dia eventually agrees to forgive Yoshiko under one condition: she sticks around for the entire two weeks to do damage control. Yoshiko isn’t sure where Dia got it into her head that a two week long sleepover with one of her best friends was a bad thing, but she sure as hell wasn’t about to tell her she didn’t mind.

Ruby, while currently a seven foot tall demon with skin as hard as iron and a gaping void in her chest where her wings connected at the back, is still very agreeable, if somewhat more easily embarrassed.

It’s not until the first real “damage control” challenge that Yoshiko begins to understand exactly why this might be considered a punishment. Dia is off complaining to Kanan in the mermaid’s cove (and probably being laughed at by Mari all the while) when Ruby approaches Yoshiko while she’s reading an online article about witchery and the affect on popular culture after magic became public. She gets the sense that Ruby was trying to approach in a way that wouldn’t startle her, but it’s hard not to notice when her mere presence makes Yoshiko’s computer glitch out and her huge shadow seems to move itself on the wall beside her.

She’s actually disheartened by how quickly she got over the surprise, though. She pops an earbud out, casually. “What’s up, Ruby?”

“Umm……Do you think there’s anything I can do to...”She fidgets in place, and wrings gigantic, clawed hands together. “I w-want to try to look less scary….”

“ _Whaaaat_?” Yoshiko lets out a forced laugh and pushes her laptop away. “You aren’t scary! N-no way!”

Ruby seems uncertain. “Oh…..but I am kind of….startling….” Well, that settles it, she guesses. If it’s her fault, then she needs to take charge and help out!

She pushes herself off the couch, and Ruby leans backwards. “Then we just need to accessorize! None of Yohane’s most valued companions can be seen as unfashionable, of course! Wait right here!” before Yoshiko is able to skid off into the distance for good, she stops herself. “Uh, am I allowed in your room?”

“S-sure.”

“Cool. Thanks!” She barges past the door quickly, before she can have second thoughts. At first she’s surprised that not everything is pink, but she shakes it off. She has to find wherever she keeps her accessories….bows, scrunchies, that sort of stuff. Yoshiko knows it’s unlikely any of her clothes will work, either, but she does see a big pink blanket that might help….

As an expert in closet cosplays, there’s enough to work with here, in her professional opinion.

She nabs any of the bows or scrunchies that she can think of a place to put, and then scours the house for a brooch. She finds a nice red one in the parent’s room (not that they ever need to know she went in there, Ever) that should help tie the blanket together the way she wants it.

Yoshiko bundles it all together and dumps it on the floor in the living room where Ruby is waiting. “None of Ruby’s cute clothes are going to fit right now, but don’t worry! The dashing Yohane can accentuate any look!”

“You don’t have to do all this, you know….” Ruby trails off, but Yoshiko will have none of it.

“I didn’t ask for excuses! The great Yohane acts as she pleases!” She boasts loudly, but when Ruby makes no move to retract the statement, Yoshiko rolls her eyes. “I wanna do this. It’s my fault you aren’t your normal cute self, so it’s up to me to spruce up this version of you as much as I can, right? It’s like a dress up party!”

“When you put it like that, it sounds kind of fun..!” Ruby is finally visibly exited, and her eyes sparkle twice as brightly. 

Yoshiko grins. “Of course it does! Now get on one knee….” She maneuvers Ruby around until she’s able to fix the pink blanket around her neck like a cloak of sorts, fitting it so that it falls on her back snugly between the wings and the brooch is off to the left. While Ruby’s at her level, she also manages to wrangle a bow onto the base of her right horn, and affix the scrunchies to the end to make the tips look much less sharp.

….if only she could do something about that mouth. She nearly flinches every time she looks at it, and she’s sure Ruby isn’t exactly comforted by the rows of teeth either. She doesn’t seem to use it for speaking – it’s a high-powered mental shout, which explains why her voice hasn’t changed – so maybe there is something Yoshiko can do for her.

“Wait right here, okay? I need to get one more thing, but it’s at my house.”

Ruby nods, and Yoshiko takes off sprinting, grabbing the broom by the front door as an afterthought. That should make the journey quicker. Hidden in a box under her bed is a relic from the most embarrassing time of her life: her cyberpunk phase. Still, it has the gas mask she was looking for, and she snaps off the clunky filters so that it’s just a faceplate with some holes in it. If she can smooth those over with a little basic magic and the excess plastic from the filters….Bingo!

She flies back over to the Kurosawa household with time to spare and holds up the mask proudly.  “A normal face mask might break, but this one should last you the two weeks! You can paint whatever you want on it, but it should make it easier for people to look at you when you’re talking, if you want it.”

“That’s probably a good idea,” Ruby agrees sheepishly. “But how are you going to get the straps to fit?”

“Eh. I’ll just make it cling to your face. You’ll still be able to pull it off anytime, it’ll just be kind of like a magnet.” She hastily enchants the plate and hands it to Ruby, who secures it with little issue. Yoshiko claps her hands. “It works! All you’re missing are the little blush lines!”

Ruby looks away, and even if she isn’t blushing visibly, Yoshiko can hear it in her voice. “Eheh, that would be an embarrassing thing to paint on. Maybe I’d better leave it plain for now.”

“If you must.” Yoshiko says, but she’s pleased to note that Ruby seems a little bit more relaxed.

They’re kicking back on the couch – Yoshiko is firmly enjoying her spot between Ruby’s legs and in front of the TV, because there truly never has been a littler spoon than she was in that moment, and because it was kind of cool to be encased in her wings but that’s beside the point – they’re relaxing when a very much unwanted thought pops into Yoshiko’s head.

“Don’t we have school tomorrow?”

**Author's Note:**

> to be continued maybe probably definitely because i made a series for it. not unlike my gratituous fantasy au, i will occasionally drop in here with one shots and stuff for the other membors of aqours and whatever fun supernatural prompt i have for them! for future reference: Chika + family are werewolves, kanan + family are mermaids, Mari is a fairy, ruby, dia, and maru are normies, yoshiko + her family are witches, Riko is a kitsune, and I have yet to pick something cool enough for Yo so ill get back to yall on that
> 
> anyways thanks so much for reading! and with this out of my system ill commence the dragon au. god i make a lot of aus. is anything on this account even happening in the canonverse


End file.
